Capital improvements accompany new water heater (Background Report)

TODAY’S REPLACEMENT of our school building’s water heater includes the installation of two new items that are required by the current building code—and for good reason. Both of them are designed not only to improve safety, but also to lengthen the life of the plumbing and of the water heater. Namely, a sediment trap (commonly called a “drip leg”) in the gas supply line, and an expansion tank in the water line. 

The rooftop vents for our school’s water heater
(Two square inlets on the left;
one round exhaust on the right.

You see that rusting cap that’s visible atop the exhaust vent? It is being replaced today, to prevent rust flakes from harming the burners down below them. Yet important as that is, it is mere maintenance. Metaphorically speaking, it’s the new capital improvements that will truly “cap off” today’s changes!

Because these small capital improvements are new to Mishkon, let me introduce them to you. Below the jump, I describe their respective functions and maintenance needs.…

Small capital improvements 

Before today, I knew nothing these two items. But now (after a little reading) I am glad that they are installed in our school building.

Sediment trap

Sediment trap,
to the left of the thermostat dial,
below the yellow gas inlet pipe

Natural gas contains a small amount of particle contaminants that can clog up the water heater’s valve or burner jets—which is what happened to our old heater, causing combustion to be so inefficient that it was unsafe (due to carbon monoxide being produced). The trap is a simple configuration of pipe pieces that settles those nuisance particles in an out-of-the-way place. As explained on one home improvement website, 

Gas line sediment traps … are typically installed below the gas valve and before the gas line enters the appliance. They are also easy to clean and should be inspected regularly to ensure they are not clogged with debris. [They] serve as a safety measure to prevent gas leaks, fires, and other hazards caused by clogs, leaks, and corrosion. 

Expansion tank

Expansion tank (blue) at upper left,
located above the water heater

The purpose of this device is explained on another home improvement website, as follows.

As the [heater’s tank of] water heats up, it expands, creating pressure inside the tank that can strain plumbing pipes over time.

To prevent this stress and extend the life of your plumbing system, a water heater expansion tank absorbs the extra pressure caused by thermal expansion.… It acts as a safety device and minimizes the risk of pressure damage, bursts, and leaks. [It] gives the hot water a place to go.… 

The same site touches upon the question of when to replace this new expansion tank: 

A water heater expansion tank typically lasts five to ten years. If you notice dripping water, mineral deposits on your pipes, decreased water pressure, or a change in water quality, it’s best to check the health of your tank and consider a replacement.